Can a platform have gatekeepers? That is, can you define as a platform something that has gatekeepers? I think not: if it's got people who stop stuff going in, you call it a "walled garden". In which case the iPhone, which had looked for, oh, at least a few weeks as though it would be a platform, is actually a walled garden. And that's not good for its long-term future, especially not now that Google has teamed up with T-Mobile to launch the first mobile based on Android, the open mobile phone platform.

Of course, if you're inside Apple's garden and standing in just the right spot, things are pretty rosy. Since the iPhone App Store opened on July 11, at least one writer has collected a cool $250,000: Steve Demeter, writer of Prism, a game that relies on the iPhone/iPod Touch's accelerometer (bit.ly/charles5).

That quarter of a million is only 70% of the revenues; Apple keeps the other 30%, or $107,000. That's good business (developers usually get a lot less than 70% of the sale price via traditional third-party distribution). And that's just one application among thousands of paid-for ones.

Only if you can get inside, though. And the walls of the garden are strangely defined. Most egregious is the case of Podcaster (bit.ly/charles6), which downloads podcasts on to an iPhone via Wi-Fi; this was rejected for "duplicating functionality of iTunes". Two things: first, it doesn't; second, why should Apple care? It's not as if iTunes is going extinct. And is Apple seriously saying it's a problem that an app does something better than iTunes does?

More recently another program called MailWrangler, which lets you check multiple Gmail accounts on the iPhone, has been rejected (bit.ly/charles7) because it "duplicates the functionality of the built-in iPhone application Mail without providing sufficient differentiation or added functionality, which will lead to user confusion". So your program can't be better than Apple's; and it can't be as good as Apple's. I think I'm starting to get the picture.

But just to be sure, I asked Apple to clarify its rules on programs' eligibility. They said they'd have an answer next day. A week later, there's still silence. As Wil Shipley, writer of the Mac application Delicious Library, points out, Apple clearly has no problem with developers duplicating each others' functionality: there are loads of sudoku programs available. It's when they "duplicate" Apple functionality it gets all huffy.

Shipley offers (at bit.ly/charles8) a simple rule: "Publish all software submitted to Apple, as long as the software isn't actively harmful to users, [or] illegal, and does not violate Apple's agreements with cell phone vendors."

Shipley is hardly delighted about Apple's rules on rejection, which it seems to have discovered down the back of a sofa in Cupertino during a latte break from approving 4,000 different iPhone apps that let you use it as a torch. He says it's "unethical and antithetical to the whole idea of an App Store for Apple to be censoring applications based on criteria they have never given to developers, and only told developers after the developers put in all the work of writing an app".

Precisely. You can't have a half-open platform; it's like being half-pregnant. Openness to all comers constitutes the difference between a platform, like Android, and a walled garden, like the iPhone (and, to be fair, pretty much every other mobile phone). RIM doesn't have gatekeepers for the BlackBerry, and Microsoft doesn't with Windows Mobile. Once Android developers get their feet under the desk, there will be some very interesting applications, and they'll all fight to be noticed on a stage even more disorganised than the iPhone App Store: the world wide web.

Google won't be setting up an Android App Store, and while T-Mobile might, I doubt it'll be as successful as Apple's, because one will be able to put pretty much anything from anywhere on to Android. All the cash will go to the developers, if they can capture it.

But I know, I know: $250,000 in three months. I don't think that any application will make that much money for Android in the next three months, and perhaps not in the coming year.

However, that's not the point of Android. It's much more about getting people to use the net all the time. Ultimately, the iPhone makes money for Google too, because it gets people using the net. Apple's not about to ban that. Which means Google will win - in time.